DE69533976T2 - Method and apparatus for direct connection in a TDMA radio transmission system - Google Patents

Description

1st area of the technique

The The invention relates to a method of radio transmission systems with multiple access time-division multiplexing (TDMA) and in particular a method for establishing a direct connection between user stations in a communication system, wherein the transmission between a base station and user stations via a variety of radio channels takes place, each of which over Timeslots features.

2. Description of the stand of the technique

The radio transmission is an integral part of mobile voice and data communications networks. After a decade of research and development become technical Standards in marketable Products and networks such as Second Generation Cordless Telephone (CT2), Digital European Cordless Telephone (DECT) and Group Special Mobile (GSM) implemented in Cordless Personal Communications W. W. W. Tuttlebee, IEEE Communications Magazine, Dec. 1992 Pages 42 to 53 are described.

Lots Radio transmission networks use a TDMA scheme that allows it a variety of portable units allows to communicate with a single base station. Set the base stations usually an interface to an external communication network ready. Nevertheless, most of today's TDMA systems have disadvantages. The Most systems operate in "base-to-portable" mode ("base station to the portable unit "), where a portable unit is a base station and its physical channels use to communicate with another portable unit, although they are in direct reach of each other. The Operating mode "base-to-portable" loads the base station over charge and power the portable units without the base station useless. Some radio transmission systems such as wireless local area networks (LANs) a direct transfer between portable units, using standard LAN procedures use, but they do not use the base station channel for the initial one Connection.

In front Recently, the Japanese Personal Handy Phone System (PHS) was developed. PHS allows there are portable units to communicate with each other directly, though the transmission over a Base station not possible is. A direct transfer between a portable unit on the originating side and a portable one Unit on the landing page is created by an unsteady cyclic channel eavesdropping (unstable cyclic channel scanning). The portable unit on the source side provides a free transmit and receive time slot in a communication channel and calls the portable unit on the destination side in the free transmission slot. In search after that sent by the portable unit on the originating side Ringing signal stops the portable unit on the landing page periodically clears all channels. After this she has detected the call signal, transmits the portable unit the landing page a confirmation signal in the reception time slot. The transmission between The portable units then begin during the transmit and receive time slots. Such a method is uneconomical because the portable units consume a lot of power when routinely listening to all channels of the system a connection to a portable unit on the originating side manufacture.

One another method of direct transmission between user stations in a communication system used in International Patent Application WO 94/05101, has the same disadvantage. There, a user station has a Control unit containing the polling message of a base station MUX2 by reconstructing the parameters of the transmission protocol the use of the MUX level changes. The Query message transmitted in a vacant channel of all radio channels of the communication system is a call message to a second user station. The second user station must listen to all channels of the system to to receive the message. Then she tries with the first user station to get in touch. Once the connection is made, forms the first user station initiating the call continues to use the total connection time one base station after.

The Disadvantages of this method are that a handset inevitably consumes a lot of power to replicate a base station, and that the second handset all channels must listen to receive a query message from the first handset. However, the battery life is in these portable units a very important one Criteria.

As more and more portable units, which are in direct range of each other, are merged into ever larger radio transmission systems, the demand for direct transmission between such portable units is likely to increase as well. For example, applications such as wireless file transfer between computers, remote terminal emulation, business card wireless exchange, and cordless telephone systems will require direct transfer between portable units make. In these applications, radio communication systems must effectively transmit both voice and data between portable units.

It is therefore an object of the present invention, a method for efficient transmission of voice and data between portable units of a TDMA radio transmission system.

It Another object of the present invention is a method for direct transmission between to provide portable units, which are suitable for the production of direct communication connection required power consumption and needed Time of portable units reduced.

A Another object of the present invention is to provide a method of direct transmission between portable units, which does not affect the standard protocols for transmission between portable units and the base station.

Further Objects and advantages of the invention will become apparent from the description, which follows, in part, they are clear from the description can be seen or become apparent when the invention is put into practice is implemented.

Summary the invention

In order to achieve the objects in accordance with the objectives of the present invention as embodied and described herein, a method for direct transmission between portable units of a TDMA radio communication system includes the following steps:
Controlling a first user station to locate a channel of a base station; Synchronizing the first user station with a first predetermined period of time within the channel of the base station during which the base station is not transmitting data and receiving data; and controlling the first user station to transmit a first paging signal within the channel of the base station during the first predetermined time period. At the same time, a second user station is controlled to locate the channel of the base station; synchronizing with the first predetermined time period and a second predetermined time period within the channel of the base station during which the base station is not transmitting data and receiving data; and upon receipt of the first paging signal, transmitting a first acknowledgment signal during the second predetermined period of time within the channel of the base station. After the first user station has received the first acknowledgment signal, transmission then takes place between the first and second user stations in an unoccupied channel. The channel of the base station may be a TDMA / TDD channel or a TDMA / FDD channel. Preferably, in a TDMA / TDD communication system, the first predetermined time period includes the transit time between the transmitting and receiving operations of the base station, and the second predetermined time period includes the transit time between the receiving and transmitting operations of the base station.

Around in a non-established channel to connect the first user station is controlled to have an unused one Canal isolated and while a third predetermined period within the unoccupied period Channel sends a second call signal. At the same time, the second user station so controlled that it locates the unoccupied channel itself with the third predetermined period and a fourth before synchronized within the unoccupied channel and while of the fourth predetermined period of time within the unoccupied channel a second confirmation signal sends after receiving the second call signal. The first and the second user station exchange within the unused one Channel data after the first user station receives the second acknowledgment signal has received.

Of the unassigned channel may be a TDMA / TDD channel or a TDMA / FDD channel be.

Around to establish a connection in an unoccupied channel alternatively, the first user station controlled so that they located a non-occupied channel and during the first predetermined Period within the channel of the base station, a channel identification signal sends that indicates the unused channel. At the same time, the second User station controlled so that it during the second predetermined Period within the channel of the base station, a channel identifier confirmation signal sends. After the first user station, the channel ID confirmation signal received, swap the first and the second user station then data in the unused channel.

The device corresponding to the first user station includes means for locating a channel of the base station; Means for synchronizing with the base station channel during a first predetermined time period during which the base station is not transmitting data and receiving data; and means for a first call within the channel of the base station during the first predetermined time period signal to send.

The Device corresponding to the second user station contains means serving to locate the channel of the base station; Medium, with the first predetermined period and a second within the channel of the base station, while the user station does not send any data and receives no data To produce synchronism; and means to during the second predetermined Period within the channel of the base station, a first confirmation signal to send after while receive the first call signal for the first predetermined period of time has been.

Short description the drawings

1 shows a cell of a DMA radio transmission system.

The 2A to 2C show packet formats commonly used in TDMA radio communication systems. 2A shows a MUX-1 packet used to exchange address data. 2 B shows a MUX-2 packet used to exchange security data. And 2C shows a MUX-3 packet used for transmission of voice and other forms of digital data.

The 3A to 3F show TDMA time division duplex (TDMA / TDD) signaling methods used to establish a direct connection between portable units according to the present invention.

The 4A to 4F show TDMA Frequency Division Duplex (TDMA / FDD) signaling methods for establishing a direct connection between portable units according to the present invention.

The 5A to 5C are flowcharts illustrating the in-band signaling method of 3A to 3F and 4A to 4F illustrate.

6 FIG. 12 is a functional block diagram of a portable unit utilizing the in-band TDMA signaling method of FIG 3A to 3F , of the 4A to 4F and the 5A to 5C applies.

Full Description of the Preferred Embodiments

Regarding 1 For example, a TDMA radio communication network typically includes a plurality of cells (a single cell is shown), each of which includes at least one base station 2 and a variety of portable units 4 Has. The base station 2 is via a central office 8th with external networks 6 such as public telephone networks or local area networks. The base station 2 is via a communication connection 10 with the central office 8th connected. The communication connection 10 For example, it may include a cable such as a fiber optic cable or a satellite connection such as a microwave satellite link. The central office 8th is via a communication connection 12 with the external networks 6 connected. The communication connection 12 For example, it may include a cable such as a fiber optic cable or a satellite connection such as a microwave satellite link.

The base station 2 communicates with the portable units 4 via radio channels, which are divided into a plurality of time slots. Each radio channel represents a predetermined frequency band. Each portable unit 4 becomes a subset of the time slots for communication with the base station 2 assigned. There are two different schemes, the out of band signaling and the inband signaling to data and control signals between the base station 2 and the portable units 4 via the time slots and corresponding channels of the TDMA radio transmission system.

In the out of band signaling scheme, two channels are used to transmit data and control signals between the base station 2 and the portable units 4 used. One of the channels, the data channel, is used for data transmission. The other channel, the control channel, is used for signaling and control. The out-of-band signaling scheme is quite powerful in voice transmission in an assigned frequency band, where the likelihood of the control channel being blocked by other users is very low, but it is not very effective in power saving in data transmission applications because the portable unit is constantly in between must switch to both channels (or each must contain separate receiving / transmitting units for each channel). This is undesirable in portable applications where battery life is extremely important.

In the in-band signaling scheme, both data and control signals are transmitted in the same channel. The inband signaling is particularly advantageous in frequency bands with spread spectrum, where there is a high probability that a channel is blocked by other users. There are two different full-duplex techniques used in in-band signaling the Time Division Multiplexing (TDD) method and the Frequency Division Multiplexing (FDD) method.

As in 3A A TDMA radio transmission system employing TDD (TDMA) communication systems employs successive frames transmitted in a channel of a base station to transmit between the base stations 2 and the portable units 4 perform. Each frame is limited by a predetermined period of time and is divided into a plurality of time slots. The duration of the time slots is determined according to the data rate and the preset frame duration. Every portable unit 4 the frame becomes a subset of the time slots for communication with the base station 2 assigned. For example, a portable unit 4 all timeslots within each frame of the channel are assigned to the base station as in 3A is shown.

The subset of time slots within the frame, that of each portable unit 4 can be further divided into two categories: transmission time slots Tx, where the base station 2 Sends data and the portable units 4 receive the transmitted data, and receive time slots Rx in which the portable units 4 Send data and the base station 2 receives the sent data. The channel of the base station of 3A For example, Fig. 15 shows frames divided into four transmission time slots Tx followed by four reception time slots Rx. Usually, the transmission time slots Tx include a time slot S which is used for synchronization and exchange of identification and control data between the base station 2 and the portable unit 4 is used, and the reception time slots Rx include a time slot R for synchronizing and exchanging identification and control data between the portable units 4 and the base station 2 is used. Timeslots S and R may not occur in every frame.

TDMA / TDD communication systems, the inband signaling for Use data transmissions, Advantageously save electricity, because the portable units due its that the exchange of data and control signals between the base station and portable units within the same channel, i.e. the channel of the base station, takes place, not between the channels have to switch.

In contrast, a TDMA radio transmission system employing FDD (TDMA / FDD) communication systems uses transmission between the base station 2 and the portable units 4 consecutive data frames sent in two separate channels. A channel, the channel for the down-link channel, ie for the connection from the transmitter to the receiver, serves to transmit data and control signals from the base station 2 to the portable units 4 , The other channel, the up-link channel, ie the link from the receiver to the transmitter, is used to transmit data and control signals from the portable units 4 to the base station 2 , Each frame is limited by a predetermined period of time and is divided into a plurality of time slots. The duration of the time slots is determined according to the data rate and the preset frame duration. Every portable unit 4 the frame becomes a subset of the time slots for communication with the base station 2 assigned. For example, a portable unit 4 all timeslots are assigned within each frame, as in 4A is shown.

The subset of time slots within the frame, that of each portable unit 4 is further divided into two categories: transmission time slots Tx, where the base station 2 Sends data in the downlink channel and the portable unit 4 receives the transmitted data in the downlink channel and receive time slots Rx at which the portable units 4 Send data in the uplink channel and the base station 2 receives the transmitted data in the uplink channel. 4A For example, Fig. 15 shows frames divided into six transmission time slots Tx in the downlink channel and six reception time slots Rx in the uplink channel. Usually, the transmission time slots Tx include a time slot S which is used for synchronization and exchange of identification and control data between the base station 2 and the portable unit 4 is used, and the reception time slots Rx include a time slot R for synchronizing and exchanging identification and control data between the portable units 4 and the base station 2 is used. Timeslots S and R may not occur in every frame.

In both the TDD-TDMA communication system and the FDD-TDMA communication system, data is transmitted via packets in time slots. The packages are usually the same length but not limited in length. The format of the packets usually differs according to the different multiplexing modes. As in 2A For example, for the call setup or MUX-1 mode, the packet format may include, for example, a preamble field and a frame alignment synchronization field, an address field for transmission of characteristics, a control field for signaling, and an error control field for error detection and correction. As in 2 B for the safety-exchange or MUX-2 mode, in which Si security parsing and / or decryption data, the packet format may include, for example, a preamble field and frame alignment synchronization field, an address field for transmission of identification data, a key field for transmission of ciphering and / or deciphering key data, a control field for signaling, and an error control field for Error detection and correction included. As in 2C For example, for the normal transmission or MUX-3 mode, the packet format may include, for example, a preamble field and a frame alignment sync field, a data field, a control panel for signaling, and an error control field for error detection and correction.

According to the present Invention is in a TDMA / TDD communication system between a primary portable unit, which is the transmission initiates, and a secondary portable unit by means of two acknowledgment exchange operations made direct connection. The first handshaking operation is performed in the channel of the base station to make a first contact between the primary portable Unity and the secondary make portable unit. After the first contact made the second handshake operation is performed to to establish a connection in an unoccupied channel.

The 3A to 3F and 5A to 5C illustrate a method for establishing a direct connection between portable units of a TDMA / TDD communication system according to the present invention. especially the 3A and 5A illustrate the first handshaking operation. Regarding 5A receives the primary portable unit in step 100 a command to initiate a transmission to the secondary portable unit. For example, in the case of direct voice transmission between the primary and secondary portable units, the command may be input by a user. For example, in the case of an automatic file backup between a computer connected to the primary portable unit and a computer connected to the secondary portable unit, the command can also be generated automatically.

In the steps 102 to 106 The primary portable unit listens for channels until it has located and synchronized with the channel of a base station. Data identifying the channels to be listened to can be stored in a memory of the primary portable unit. The data may be permanently stored in the memory or downloaded from the base station. In step 102 The primary portable unit tunes in to a particular channel, and in step 104 She then tries to locate and sync radio signals from the base station in the particular channel. When the step 104 fails, the primary portable unit goes to step 105 to check if all channels have been intercepted. When in step 105 If it is determined that not all channels have been intercepted, the primary portable unit will switch in step 106 to another channel and then returns to the step 104 back. When the step 104 is successful, the process goes on with the step 108 continued. Locating the radio signals of the base station channel and synchronizing with these signals within the particular channel may be performed by the base station transmitting a MUX-1 packet during timeslot S and the primary portable unit sending the particular channel to MUX-1. Listen to the package and discover it in this channel. Once synchronized with the radio signals of the base station channel, the timer circuit of the primary portable unit may indicate predetermined periods within the channel of the base station, such as the sweep time Tps, which is the time period between the transmission mode and the reception mode the base station, and the transit time Tpr, which is the period between the receive mode and the base station transmit mode, as in 3A is shown.

In step 108 The primary portable unit in the channel of the base station transmits a call packet CP during a first predetermined period, preferably the sweep time Tps, and at step 110 It listens to the channel for an acknowledgment packet AP sent by the secondary portable unit in the channel of the base station during a second predetermined period, preferably the sweep time Tpr. For example, the call packet CP and the acknowledgment packet AP may have the MUX-1 packet structure as in 2A is shown.

During operation of the primary portable unit described above, the secondary portable unit wakes up at regular intervals and synchronizes with a channel of the base station when it is not communicating with the base station, that is, when it is in sleep mode. In step 200 wakes up the secondary portable unit from sleep mode, and in step 202 It tunes in to a particular channel, which may be a base station channel to which the secondary portable unit was already tuned before entering sleep mode. In step 204 the secondary portable unit attempts to locate and synchronize radio signals within the particular channel. The localization and the synchronization with radio signals of the channel of the base station within the particular channel can by in that the base station transmits a MUX-1 packet during the time slot S and the secondary portable unit listens to the particular channel for the MUX-1 packet and discovers it in the particular channel. Once synchronized with the radio signals of the base station channel, the secondary portable unit timer circuit may indicate predetermined periods of time within the channel of the base station, such as the sweeps Tps and Tpr.

When the step 204 fails, the secondary portable unit goes to step 205 to check if all channels have been intercepted. Data indicating the channels to be listened to can be stored in a memory of the secondary portable unit. The data may be permanently stored in the memory or downloaded from the base station. When in step 205 If it is determined that not all channels have been intercepted, the secondary portable unit will switch in step 206 to another channel and then returns to the step 204 back. When the step 204 runs successfully, sets the secondary portable unit in the step 208 whether it is being called by the base station. This may take place by the base station transmitting a MUX-1 packet requesting it to establish a connection to the secondary portable unit during the time slot S within the channel of the base station and by having the secondary portable unit transmit the channel of the base station to the base station Listening to the MUX-1 packet and discovering it in the channel of the base station. If the secondary portable unit in step 208 determines that it is being called by the base station, it starts in step 210 the operating mode "base-to-portable". The "base-to-portable" mode of operation is known in the art, as shown in the Digital European Cordless Telephone (DECT) Common Interface, European Telecommunications Standards Institute, 1992, incorporated herein by reference. If the secondary portable unit in step 208 determines that it is not being called by the base station, the process goes to the step 212 continued.

In step 212 the secondary portable unit listens to the call packet CP sent by the primary portable unit in the cycle time Tps, as in 3A is shown. If the secondary portable unit in step 212 the call packet CP discovered, sends it in step 214 a confirmation packet AP in the cycle time Tpr. If the secondary portable unit in step 212 If the call packet CP is not detected, the process goes to the step 216 continued, in which the secondary portable unit determines whether a timeout interval has expired. If the secondary portable unit in step 216 determines that the time monitoring interval has not expired, the process goes to step 208 back. If the secondary portable unit in step 216 determines that the timeout interval has expired, the periodic wakeup operation ends in step 218 , and the secondary portable unit can return to sleep mode.

As described above, the primary portable unit transmits in the step 108 the call packet CP, and in the step 110 listen for the acknowledgment packet AP sent by the secondary portable unit. The process then goes to the step 112 Continuing in which the primary portable unit checks to see if the secondary portable unit is stepping 214 transmitted acknowledgment packet AP is detected. If the discovery of the confirmation packet AP in step 112 successful, the operation of the primary portable unit goes to step 114 in that the primary and secondary portable units perform the second handshake operation to establish a connection in a non-busy channel.

However, the transmission of the acknowledgment packet AP by the secondary portable unit may not be outstanding, for example, because the secondary portable unit may have been in a different frequency channel or in idle mode, as in FIG 3A is shown. To account for this scenario, the primary portable unit checks in step 112 if it does not detect the confirmation packet AP, whether in step 116 a timeout interval has expired. If the timeout interval in step 116 has not expired, the process switches to the steps 108 and 110 back in which the primary portable unit retransmits the call packet CP and then listens to the acknowledgment packet AP.

On the other hand, the secondary portable unit retransmits the acknowledgment packet AP when it does not receive confirmation from the primary portable unit that the acknowledgment packet AP has been received. An acknowledgment that the primary portable unit has received the acknowledgment packet can be made in many ways. In step 220 For example, the secondary portable unit is looking for multiple call packets CP in the turnaround time Tps. If the secondary portable unit in step 220 If several call packets CP are detected in the cycle time Tps, the process goes to step 214 back to resend the AP acknowledgment packet. If the secondary portable unit in step 220 the call packets CP are not detected in the cycle time Tps, it is confirmed that the primary portable unit has received the confirmation packet AP, and the operation of the secondary portable unit continues with the step 222 in which the primary and secondary portable units perform the second handshake operation to establish a connection in an unoccupied channel manufacture.

If the timeout interval in step 116 has expired, the process goes to the step 105 back, where the primary portable unit detects if all channels have been intercepted. When the primary portable unit in step 105 determines that all channels have been intercepted, the first handshaking operation ends. The process, however, comes with the step 114 continued to attempt to establish the communication link between the primary and secondary portable units via the second handshaking operation. If the secondary portable unit in step 205 If it is determined that all the channels have been intercepted, the sequence also goes to the step 222 to try to use the second handshaking operation.

The 3B to 3D and 5B show the second handshaking operation between the primary and secondary portable units of a TDMA / TDD communication system according to a first embodiment of the present invention. In step 300 The primary portable unit listens for channels to find an unoccupied channel. Data indicating the channels to be listened to can be stored in the memory of the primary portable unit. The data may be permanently stored in the memory or downloaded from the base station. In step 302 The primary portable unit transmits primary beacon signals (PBS) in the unoccupied channel during transmission slots, and in the step 304 listen during reception time slots to secondary radio acknowledgment signals BAS, as in 3B is shown. The primary radio signals PBS and the secondary radio acknowledgment signals BAS may have the MUX-1 format as in 2A is shown.

At the same time, the secondary portable unit listens to channels listening for primary radio signals PBS. Data indicating the channels to be listened to can be stored in a memory of the secondary portable unit. The data may be permanently stored in the memory or downloaded from the base station. In step 400 the secondary portable unit sets itself on an unoccupied channel, and in step 402 listen to PBS primary radio signals. In step 404 The secondary portable unit determines whether it has located and synchronized with primary radio signals PBS sent from the primary portable unit. Once synchronized with the primary radio signals PBS, the timer circuit of the secondary portable unit indicates the transmit and receive time slots. If the secondary portable unit in step 404 determines that it has localized and synchronized with primary radio signals PBS, transmits the secondary portable unit in step 406 during reception time slots, secondary radio acknowledgment signals BAS in the particular channel as in 3B is shown, and hears when the primary portable unit with the exchange of data in step 408 starts. If the secondary portable unit in step 404 determines that it has not localized any primary radio signals PBS and is not synchronized with them, checks them in step 410 whether a first timeout interval has expired. If the first timeout interval in step 410 has not expired, the process goes to step 402 back, in which the secondary portable unit listens for primary radio signals PBS in the particular channel. If the first timeout interval in step 410 has expired, represents the secondary portable unit in the step 412 determines if a second timeout interval has expired. If the second timeout interval in step 412 has not expired, the secondary portable unit turns in step 414 on a new unoccupied channel and returns to the step 402 back to listen for primary radio signals PBS in the new channel. If the second timeout interval in step 412 has expired, the second handshaking operation ends, and the secondary handheld unit returns in step 416 go back to sleep.

At the same time, the primary portable unit puts in step 306 determines whether it has received secondary beacon signals - BAS during receive time slots, if the reception of the secondary acknowledge beacons BAS in step 306 was successful, the process goes on with the step 308 in which the primary and secondary portable units begin to exchange data as in 3D is shown. When the primary portable unit in step 306 determines that the secondary radio acknowledgment signals BAS have not been received, the primary portable unit checks in step 310 whether a timeout interval has expired. If the timeout interval in step 310 has not expired, the process switches to the steps 302 and 304 back in which the primary portable unit once again transmits primary radio signals PBS and listens for secondary radio acknowledgment signals BAS. If the timeout interval in step 310 has expired, the primary portable unit checks in step 312 whether all channels have been intercepted. When in step 312 If it is determined that not all channels have been intercepted, the primary portable unit will switch in step 314 to a new unoccupied channel, and the process goes to the steps 302 and 304 back in which the primary portable unit transmits primary radio signals PBS during transmission time slots in the new channel and to secondary radio acknowledgment signals BAS during reception time slots in the new channel listens. When in step 312 all channels have been listened to, the second handshake operation ends in step 316 , In this scenario, the secondary portable unit is likely to be in the base-to-portable mode or outside the direct wireless range of the primary portable unit. In step 316 Can the primary portable unit in the attempt to connect the secondary portable unit through the base station 4 to initiate a "portable-to-base" call.

The data exchange of the steps 308 and 408 who in 3D may include the transmission of security data, such as an encryption key and / or a decipher key, in a MUX-2 format and / or the transmission of voice and other types of digital data in a MUX-3 format.

According to one second embodiment of the present invention the functions of the primary and the secondary portable unit of the TDMA / TDD communication system at the second Acknowledgment exchange operation described above with reference to the first embodiment described, be reversed. In this case, the secondary portable hears Unit channels to find an unused channel sends secondary radio signals in the unoccupied channel and listen for primary radio acknowledgment signals. simultaneously hears the primary portable Unit channels from, taking on the secondary Radio signals are being listened to by the secondary portable unit and after receiving the secondary radio signals it sends primary Acknowledgment beacon signals.

The 3E to 3F and 5C illustrate the second handshake operation of the primary and secondary portable units of a TDMA / TDD system according to a third embodiment of the present invention. In step 500 the primary portable unit listens for channels until it finds an unoccupied channel and records an unoccupied channel identifier (UCID) indicating the unoccupied channel. Data indicating the channels to be listened to can be stored in the memory of the primary portable unit. The data may be permanently stored in the memory or downloaded from the base station. In step 502 the primary portable unit returns to the base station channel in step 504 It transmits a primary radio signal during the cycle time Tps in the channel of the base station, and in the step 506 listen to a secondary acknowledgment signal during the transit time Tpr, as in 3E is shown. The primary radio signal contains the identifier of the unused channel UCID. The secondary radio acknowledgment signal indicates that the secondary portable unit has successfully received the idle channel identifier UCID sent from the primary portable unit. The primary radio signal and the secondary radio acknowledgment signal may have the MUX-1 format, as in 2A is shown.

At the same time, the secondary portable unit remains in step 600 in the channel of the base station, and in step 602 listen to the primary radio signal in the channel of the base station during the cycle time Tps. In step 604 The secondary portable unit determines whether it has received the primary radio signal during the transit time Tps in the channel of the base station. If the secondary portable unit in step 604 has received the primary radio signal, sends it in step 606 during the transit time Tpr in the channel of the base station, the secondary radio acknowledgment signal as in 3E is shown. If the secondary portable unit in step 604 has not received the primary radio signal, it checks in step 608 whether a timeout interval has expired. If the timeout interval in step 608 has not expired, the process goes to step 602 back, in which the secondary portable unit listens to the primary radio signal during the cycle time Tps in the channel of the base station. If the timeout interval in step 608 has expired, the process ends in step 610 successful, and the secondary portable unit can return to sleep mode.

As described above, the primary portable unit transmits in the step 504 the primary radio signal, and in step 506 listen for the secondary acknowledgment signal. The process then goes to the step 508 continued, in which the primary portable unit checks whether it detects the secondary radio acknowledgment signal. If the secondary radio acknowledgment signal in step 508 can be detected successfully, turns on the primary portable unit in step 510 to the unoccupied channel indicated by the unused channel identifier (UCID) and starts in step 512 with the exchange of data, as in 3F is shown.

However, the transmission of the secondary radio acknowledgment signal by the secondary portable unit may not be due, for example, because the channel of the base station is blocked due to transmission between other user stations, and thus the secondary portable unit has never received the primary radio signal. To account for this scenario, the primary portable unit checks in step 514 whether a timeout interval has expired when in step 508 determines that the secondary radio acknowledgment signal has not been received. If the timeout interval in step 514 has not expired, the process switches to the steps 504 and 506 back in which the primary portable unit re-transmits the primary radio signal and listens for the secondary radio acknowledgment signal. If the timeout interval in step 514 has expired, the process ends in step 516 in which the primary portable unit in the attempt to connect with the secondary portable unit via the base station 4 to initiate a "portable-to-base" call.

In the steps 606 and 612 Once again, the secondary portable unit transmits the secondary radio acknowledgment signal when it receives no acknowledgment from the primary portable unit that the secondary radio acknowledgment signal has been received. An acknowledgment that the primary portable unit has received the secondary radio acknowledgment signal can be made in many ways. For example, the secondary portable unit stops in step 612 Look for several primary radio signals in the cycle time Tps. If the secondary portable unit in step 612 If several primary radio signals are detected in the cycle time Tps, the process goes to step 606 back to retransmit the secondary acknowledgment signal. If the secondary portable unit is the primary radio signals in step 612 can not detect, this confirms that the primary portable unit has received the secondary radio acknowledgment signal, and the operation of the secondary portable unit becomes the step 614 continued, in which the secondary portable unit switches to the unoccupied channel, which is identified by the identifier of the unoccupied channel (UCID), and in step 616 she begins with the exchange of data.

According to one fourth embodiment of the present invention the functions of the primary and the secondary portable unit of the TDMA / TDD communication system at the second Acknowledgment exchange operation described above in the third embodiment was, be reversed. In this case, the secondary portable hears Unit channels to find an unused channel sends during the Throughput time Tpr in the channel of the base station a secondary radio signal and then listen for a primary one Beacon acknowledgment signal while the cycle time Tps in the channel of the base station. The secondary radio signal contains one Identifier of an unused channel that contains the unused channel indicates. At the same time, the primary portable unit is listening to the from the secondary portable Unit sent secondary Radio signal, and after receiving the secondary radio signal it transmits the primary one Acknowledgment beacon signal.

The Embodiments described above Advantageously limit the power consumption and the time required primary and the secondary portable unit of a TDMA / TDD communication system in making a direct connection by reducing the lead times Use Tps and Tpr in the base station channel to perform the first handshaking operation perform, and in the case of the third and fourth embodiments, the second handshaking operation perform. About that In addition, this does not affect the standard protocols for transmission between the base station and the portable units. Significant is also that this does not affect the physical radio channels of the base station has, thereby increasing the performance the base station is retained for transmission between the base station and other portable units.

If however, the cycle times Tps and Tpr are short-lived the base station can be controlled to operate for predetermined periods of time during a or more of the plurality of consecutive frames of the channel the base station is switched off. For a fast access time preferably, the base station may be controlled so that they are in every frame for predetermined periods (usually less than a few percent of the frame duration) is turned off. The predetermined periods be used to make a direct connection between portable Unit reserved. In this case, include the predetermined periods preferably the processing times Tpr or Tps.

The The present invention is also applicable to TDMA / FDD communication systems. In this Case, the first handshaking operation in the downlink and in the uplink channel carried out, initial contact between the primary and secondary portable units manufacture. After the initial contact has been made, the second handshake operation performed to run in a pair of idle channels to make a connection.

The 4A to 4F and 5A to 5C illustrate a method for establishing a direct connection between portable units of a TDMA / FDD communication system according to the present invention. especially the 4A and 5A illustrate the first handshaking operation. The operation is similar to the first handshaking operation described above with respect to the TDMA / TDD communication system, but the transmission between the base station and the portable units takes place over two separate frequency channels: the downlink channel and the uplink channel.

As in 4A shown, sends the primary portable unit during a first predetermined period Tps a call packet CP in the downlink channel and listen for an acknowledgment packet AP sent by the secondary portable unit during a second predetermined period Tpr in the uplink channel. The base station is controlled to be turned off during the first predetermined period Tps and the second predetermined time period Tpr within the downlink and uplink channels. Preferably, the first period Tps and the second period Tpr are located directly next to the control slots S and R.

The secondary portable unit on the other hand listens channels listening to the call packet CP from the primary portable Unit in the first predetermined period within the Downlink channel was sent. After she has discovered the call packet CP, sends the secondary portable unit the confirmation package AP in the second predetermined period within the uplink channel. If the primary portable unit the confirmation package AP receives, will the operation of the primary portable unit continued with the second handshaking operation.

If the secondary portable unit a confirmation receives that the confirmation packet AP from the primary portable unit has been received, for example, by determines that the primary portable unit the transmission of the call packet CP has completed, the operation of the secondary portable Unit continued with the second handshaking operation.

The 4B to 4D and 5B illustrate the second handshake operation of the primary and secondary portable units of a TDMA / FDD system according to a fifth embodiment of the present invention. This operation is similar to the second handshake operation of a TDMA / TDD communication system described above with reference to the first embodiment. In this case, the primary portable unit listens to channels to find a pair of unoccupied channels: a first unoccupied channel and a second unoccupied channel. The primary portable unit then transmits primary radio signals in the first unoccupied channel and listens for secondary radio acknowledgment signals in the second unoccupied channel. The primary radio signals may contain data indicating the second unoccupied channel. At the same time, the secondary portable unit listens to channels listening for primary radio signals transmitted from the primary portable unit, and after having received the primary radio signals, transmits secondary radio acknowledgment signals in the second unoccupied channel. When the primary portable unit receives the secondary radio acknowledgment signals, it begins to communicate with the secondary portable unit in the first and second unoccupied channels, as in FIG 4D is shown. When the secondary portable unit receives an acknowledgment that the primary portable unit has received the secondary radio acknowledgment signals, for example, by determining that the primary portable unit has completed the transmission of the primary radio signals, operation of the secondary portable unit continues with it; that it starts exchanging data in the first and second unoccupied channels, as in 4D is shown.

According to one sixth embodiment of the present invention the functions of the primary and the secondary portable unit of the TDMA / FDD communication system in the second handshaking operation referred to above with reference to FIG to the fifth embodiment described, be reversed. In this case, the secondary portable hears Unit channels to find a pair of unoccupied channels: a first one unoccupied channel and a second unoccupied channel. The secondary portable Unit then sends secondary Radio signals in the first unoccupied channel and listen for primary radio acknowledgment signals in the second unoccupied channel. The secondary radio signals can be data containing the second unoccupied channel. simultaneously hear that primary portable unit channels from, taking on the secondary Radio signals, and after receiving the secondary radio signals, it transmits primary radio acknowledgment signals in the second unoccupied channel.

The 4E and 4F such as 5C illustrate the second handshaking operation of the primary and secondary portable units of an FDD / TDMA communication system according to a seventh embodiment of the present invention. This operation is similar to the second handshake operation of a TDMA / TDD communication system described above with reference to the third embodiment.

In this case, the primary portable unit listens for channels until it finds a pair of unoccupied channels and records an unoccupied channel (UCID) identifier indicating the unoccupied channels. As in 4E 12, the primary portable unit then transmits a primary radio signal containing the idle channel identifier (UCID) during the first predetermined period of time in the downlink channel, and during the second predetermined period of time, it listens for a secondary radio acknowledgment signal Uplink channel. The secondary radio acknowledgment signal indicates that the secondary portable unit has successfully received the idle channel identifier (UCID) sent from the primary portable unit.

At the same time, during the first predetermined time period within the downlink channel, the secondary portable unit listens for the primary radio signal, and after having received the primary radio signal, transmits the secondary radio acknowledgment signal in the uplink period in the second predetermined time period. When the primary portable unit receives the secondary radio acknowledgment signal, it starts exchanging data with the secondary portable unit in the first and second unoccupied channels indicated by the idle channel identifier (UCID), as shown in FIG 4F is shown. When the secondary portable unit receives an acknowledgment that the primary portable unit has received the secondary radio acknowledgment signal, for example, by determining that the primary portable unit has completed the transmission of the primary radio signal, operation of the secondary portable unit continues with it; that it starts exchanging data in the first and second unoccupied channels indicated by the unused channel identifier (UCID), as in 4F is shown.

According to one eighth embodiment of the present invention the functions of the primary and the secondary portable unit of the TDMA / FDD communication system at the second Acknowledgment exchange operation described above with reference to the seventh embodiment described, be reversed. In this case, the secondary portable hears Unit channels until she finds a pair of unoccupied channels, and lists the ID of an unused channel (UCID), which is the unused one channels indicates. The secondary portable unit then sends while of the second predetermined period within the uplink channel a secondary one Radio signal containing the identifier of the unused channel (UCID), and listen while of the first predetermined period in the downlink channel to a primary radio acknowledgment signal. The primary Beacon acknowledgment signal indicates that the primary portable unit sent by the secondary portable unit ID of the unused channel (UCID) has been successfully received.

simultaneously listen to the primary portable unit during of the second predetermined period within the uplink channel on the secondary Radio signal, and after receiving the secondary radio signal it transmits the primary radio acknowledgment signal in the first predetermined period in the downlink channel. If the secondary portable unit is the primary radio acknowledgment signal receives she starts, with the primary portable unit in the first and second unoccupied channels, each by the identifier for the unused channel (UCID) to exchange data. If the primary portable unit a confirmation receives that the secondary portable unit is the primary radio acknowledgment signal has received, for example, by noting that the secondary portable Unit the transmission of the secondary Radio signal has completed, the operation of the primary portable Unit continued to work with the exchange of data in the first and second unoccupied channel begins by the identifier of the unused channel (UCID) can be identified.

The Embodiments described above Advantageously limit the power consumption and the time required primary and the secondary portable unit of a TDMA / FDD communication system in making a direct connection by having a first predetermined period within the downlink channel and a second predetermined period within the uplink channel use to perform the first handshake operation, and in the case of the seventh and eighth embodiments, the second handshaking operation perform. About that In addition, this does not affect the standard protocols for transmission between the base station and the portable units .. of importance is also that this does not affect the physical radio channels of the base station which has the power of the Base station is maintained, which is for transmission between the base station and other portable units.

In a further manifestation, each portable unit 4 the radio transmission system to be assigned a unique identification number. A group of peers, for example, a group of portable units 4 can act, which belong to colleagues in the same working group, is formed by the respective identification numbers of the portable units 4 be assigned to a group ID number within the group of equals. The ID numbers in the group of equals usually belong to the portable units, which are usually in direct radio range of each other. The information about the group of equals can be obtained from the user of each portable unit 4 entered or transmitted by standard control signal method and in the portable A units 4 get saved.

Around a connection between the primary and the secondary portable Unit manufacture, represents the primary portable unit in this Case first determines if the identification number of the secondary portable unit is part the group (s) of equals to whom the secondary portable Unit belongs. If there is a clear match gives, represents the primary portable unit connects to the secondary portable unit, taking the steps outlined briefly above. Otherwise becomes a "standard portable-to-base" procedure carried out. The advantages of this procedure are that the base station only handles the traffic outside the group of equals the primary portable Unit takes place.

A direct transmission between the primary and secondary portable units, as described above in the various embodiments of the present invention, may be with a portable unit 4 be realized, as in 6 is shown. The primary and secondary portable units each contain a radio module 700 which transmits and receives a digital TDMA data stream with data and control signals over a radio link. A radio interface 710 is between the radio module 700 and a first digital processor 720 connected. The radio interface 710 usually stores the data and control signals to be transmitted, and also stores the data and control signals that are received. Controlled by a first program in memory 730 can be stored, controls the first digital processor 720 the operation of the portable unit 4 , The first digital processor 720 For example, it may be an ordinary microprocessor or a digital signal processing unit. The first digital processor 720 In particular, the first program executes the operation of the portable unit 4 to control. The control functions performed by the execution of the first program typically include the selective activation and control of the modules of the portable unit 4 , For example, execution of the first program may be performed by the first digital processor 720 control the channel frequency to which the radio module 700 to receive data over the radio link, or it may be the channel frequency of the radio module 700 control to send data over the radio link.

The timing and synchronization of the portable unit 4 with the received data stream are usually from the radio interface 710 and a timer circuit 735 performed. Specifically, the radio interface generates 710 in response to synchronization data in the received data stream, a synchronization signal. The synchronization signal may represent, for example, consecutive frames in the received data stream. That of the radio interface 710 generated synchronization signal is the timer circuit 735 which generates timing signals in response to the synchronization signal. For example, the timing signals may represent one or more predetermined time periods in each frame of the data stream. The from the timer circuit 735 generated time signals are the first digital processor 720 fed to the time and sequence control.

A second digital processor 740 is between the first digital processor and an external interface 750 connected. Controlled by a second program in memory 730 can be stored, the second digital processor processes 740 usually data from the radio module 700 to be sent, as well as data sent by the radio module 700 be received. The processing of the data by the radio module 700 may include error detection on the received data and its correction, and the formulation and addition of error detection and correction data to the data stream for transmission. The second digital processor 740 For example, it may be an application specific integrated circuit (ASIC) dedicated to digital signal processing. In addition, the functionality of the first digital processor 720 and the functionality of the second digital processor 740 be brought together in a common entity. The external interface 750 is with one or more external units 760 (not shown) communicating information contained in the received data stream to the user and generating / generating input signals in accordance with the user input. The external unit 760 may be, for example, a speaker and a microphone or a computer system. The external interface 750 Brings the received data from the second digital processor 740 have been processed into a specific, for the external unit 760 recognizable form. The conditioning of the received data may be, for example, the conversion of the received data from the digital to the analog form and the provision of an output signal corresponding to the analog form and the external unit 760 can control. The external interface 750 also brings that from the external unit 760 generated input signals into a specific, for the second digital processor 740 recognizable form. The conditioning of the input signals may include, for example, digitizing the analog input signals.

According to the present invention, the first program in a TDMA / TDD communi cation system, that of the first digital processor 720 the primary and secondary portable unit is running, routines that run in the 3A to 3F and in the 5A to 5C are shown and described above with reference to the first to fourth embodiments. As in the 3A and 5A is shown, the first program has the first digital processor 720 thus, the primary portable unit, the radio module 700 controlling the primary portable unit to listen to radio channels and to try to locate and synchronize with each radio channel the base station channel radio signals in the received data stream. When synchronized with the radio signals of the base station channel, the timer circuit performs 735 the primary portable unit to the first digital processor 720 Time signals indicative of predetermined periods within the channel of the base station, such as the cycle times Tps and Tpr, as in FIG 3A is shown. The first program then controls the first digital processor 720 in such a way that it generates a call packet CP, the call packet CP to the radio module 700 forwards, the radio module 700 controls to send the call packet CP during the transit time Tps within the channel of the base station and listen for an acknowledgment packet AP in the transit time Tpr within the channel of the base station.

The first program of the secondary portable unit has the first digital processor 720 on, the radio module 700 to control the secondary portable unit to periodically wake up, listen to radio channels, and attempt to locate and synchronize radio signals of the channel of a base station in the received data stream at each radio channel. When synchronized with the radio signals of the base station channel, the timer circuit generates 735 the secondary portable unit time signals indicating predetermined periods within the channel of the base station, such as the cycle times Tps and Tpr. The first program then controls the first digital processor to determine whether there is a call packet CP in the data stream received during the cycle time Tps. When the call packet CP has been received in the cycle time Tps, the first program controls the first digital processor 720 such that it generates an acknowledgment packet AP, the acknowledgment packet AP to the radio module 700 forwards and the radio module 700 controls to send the acknowledgment packet AP during the transit time Tpr within the channel of the base station.

The second handshaking operation included in the 3B to 3F and in the 5B and 5C According to the various embodiments described above, is also controlled by the first program of the primary and the secondary portable unit.

In a TDMA / FDD communication system, the first one of the first digital processor contains 720 the primary and secondary portable units executed routines that are in the 4A to 4F and in the 5A to 5C are shown and described above with reference to the fifth to eighth embodiments. As in the 4A and 5A is shown, the first program has the first digital processor 720 thus, the primary portable unit, the radio module 700 controlling the primary portable unit to listen to radio channels and to try to locate and synchronize with each radio channel the base station channel radio signals in the received data stream. When synchronized with the radio signals of the base station channel, the timer circuit performs 735 the primary portable unit to the first digital processor 720 Timing signals indicative of predetermined periods such as the cycle times Tps and Tpr are indicated as in 4A is shown. The first digital processor 720 thus indicates the current radio channel as the downlink channel of the base station. Subsequently, the first digital processor must 720 indicate the uplink channel of the base station. This can happen in many ways. For example, the uplink channel of the base station may be shifted by a fixed amount in the frequency domain, or the pairs of base station consisting of downlink channel and uplink channel may be fixed and stored in memory 130 get saved. In another embodiment, data indicating the uplink channel of the base station may be included in the received data stream. The first program then controls the first digital processor 720 such that it generates a call packet CP, the call packet CP to the radio module 700 forwards, the radio module 700 so that it transmits the call packet CP during the period Tps in the downlink channel of the base station controls the radio module 700 controls to select the uplink channel of the base station and listen for an acknowledgment packet AP in the period Tpr in the uplink channel of the base station.

The first program of the secondary portable unit has the first digital processor 720 on, the radio module 700 be controlled so that it wakes up at regular intervals, listening to radio channels and tries on each radio channel to locate and synchronize radio signals of the channel of a base station in the received data stream. When synchronized with the radio signals of the base station channel, the timer circuit generates 735 the secondary portable unit time signals, the predetermined time rooms, such as the cycle times Tps and Tpr. The first digital processor 720 thus indicates the current radio channel as the downlink channel of the base station. Subsequently, the first digital processor must 720 indicate the uplink channel of the base station. This again can be done in many ways as described above with respect to the primary portable unit. The first program then controls the first digital processor 720 such that it determines whether a call packet CP is received in the downlink channel of the base station during the period Tps. When the call packet CP has been received, the first program controls the first digital processor 720 such that it generates an acknowledgment packet AP, the acknowledgment packet AP to the radio module 700 forwards, the radio module 700 so controls that it selects the uplink channel of the base station and the radio module 700 so that it sends the acknowledgment packet AP during the period Tpr in the uplink channel of the base station.

The second handshaking operation included in the 4B to 4F and in the 5B and 5C is shown in accordance with the various embodiments described above, equally controlled by the first program of the primary and the secondary portable unit.

• – Das beschriebene Verfahren kann um die folgenden Schritte erweitert werden: Steuern der ersten Benutzerstation in der Weise, dass sie den zweiten Funkkanal lokalisiert; Steuern der ersten Benutzerstation in der Weise, dass sie während eines dritten vorher festgelegten Zeitraums innerhalb des zweiten Funkkanals ein zweites Rufsignal sendet.
• – Die erste Benutzerstation sendet während Sendezeitschlitzen innerhalb des zweiten Funkkanals Daten und empfängt Daten während Empfangszeitschlitzen innerhalb des zweiten Funkkanals, und der dritte vorher festgelegte Zeitraum umfasst einen der Sendezeitschlitze.
• – Das beschriebene Verfahren kann um die folgenden Schritte erweitert werden: Steuern der zweiten Benutzerstation in der Weise, dass sie den zweiten Funkkanal lokalisiert; Synchronisieren der zweiten Benutzerstation mit dem dritten vorher festgelegten Zeitraum und einem vierten vorher festgelegten Zeitraum innerhalb des zweiten Funkkanals; und Steuern der zweiten Benutzerstation in der Weise, dass sie während des vierten vorher festgelegten Zeitraums innerhalb des zweiten Funkkanals ein zweites Bestätigungssignal sendet, nachdem sie das zweite Rufsignal während des dritten vorher festgelegten Zeitraums empfangen hat.
• – Die erste Benutzerstation sendet während Sendezeitschlitzen innerhalb des zweiten Funkkanals Daten und empfängt Daten während Empfangszeitschlitzen innerhalb des zweiten Funkkanals, und die zweite Benutzerstation sendet während der Empfangszeitschlitze innerhalb des zweiten Funkkanals Daten und empfängt Daten während der Sendezeitschlitze innerhalb des zweiten Funkkanals, wobei der dritte vorher festgelegte Zeitraum einen der Sendezeitschlitze umfasst und wobei der vierte vorher festgelegte Zeitraum einen der Empfangszeitschlitze umfasst.
• – Einen Schritt des Austauschs von Daten zwischen der ersten und der zweiten Benutzerstation innerhalb des zweiten Funkkanals, nachdem die erste Benutzerstation das zweite Bestätigungssignal während des vierten vorher festgelegten Zeitraums innerhalb des zweiten Funkkanals empfangen hat.
• – Die erste Benutzerstation sendet während Sendezeitschlitzen innerhalb des zweiten Funkkanals Daten und empfängt Daten während Empfangszeitschlitzen innerhalb des zweiten Funkkanals, und die zweite Benutzerstation sendet Daten während der Empfangszeitschlitze innerhalb des zweiten Funkkanals und empfängt Daten während der Sendezeitschlitze innerhalb des zweiten Funkkanals, wobei der dritte vorher festgelegte Zeitraum einen der Sendezeitschlitze umfasst und wobei der vierte vorher festgelegte Zeitraum einen der Empfangszeitschlitze umfasst.
• – Das beschriebene Verfahren kann um die folgenden Schritte erweitert werden: Steuern der zweiten Benutzerstation in der Weise, dass sie den zweiten Funkkanal lokalisiert; Steuern der zweiten Benutzerstation in der Weise, dass sie während eines dritten vorher festgelegten Zeitraums innerhalb des zweiten Funkkanals ein zweites Rufsignal sendet.
• – Die zweite Benutzerstation sendet während Sendezeitschlitzen innerhalb des zweiten Funkkanals Daten und empfängt Daten während Empfangszeitschlitzen innerhalb des zweiten Funkkanals, und der dritte vorher festgelegte Zeitraum umfasst einen der Sendezeitschlitze.
• – Das beschriebene Verfahren kann um die folgenden Schritte erweitert werden: Steuern der ersten Benutzerstation in der Weise, dass sie den zweiten Funkkanal lokalisiert; Synchronisieren der ersten Benutzerstation mit dem dritten vorher festgelegten Zeitraum und einem vierten vorher festgelegten Zeitraum innerhalb des zweiten Funkkanals; und Steuern der ersten Benutzerstation in der Weise, dass sie während des vierten vorher festgelegten Zeitraums innerhalb des zweiten Funkkanals ein zweites Bestätigungssignal sendet, nachdem sie das zweite Rufsignal während des dritten vorher festgelegten Zeitraums empfangen hat.
• – Die zweite Benutzerstation sendet während Sendezeitschlitzen innerhalb des zweiten Funkkanals Daten und empfängt Daten während Empfangszeitschlitzen innerhalb des zweiten Funkkanals, und die erste Benutzerstation sendet während der Empfangszeitschlitze innerhalb des zweiten Funkkanals Daten und empfängt Daten während der Sendezeitschlitze innerhalb des zweiten Funkkanals, wobei der dritte vorher festgelegte Zeitraum einen der Sendezeitschlitze umfasst und wobei der vierte vorher festgelegte Zeitraum einen der Empfangszeitschlitze umfasst.
• – Einen Schritt des Austauschs von Daten zwischen der ersten und der zweiten Benutzerstation innerhalb des zweiten Funkkanals, nachdem die zweite Benutzerstation das zweite Bestätigungssignal während des vierten vorher festgelegten Zeitraums innerhalb des zweiten Funkkanals empfangen hat.
• – Die zweite Benutzerstation sendet während Sendezeitschlitzen innerhalb des zweiten Funkkanals Daten und empfängt Daten während Empfangszeitschlitzen innerhalb des zweiten Funkkanals, und die erste Benutzerstation sendet Daten während der Empfangszeitschlitze innerhalb des zweiten Funkkanals und empfängt Daten während der Sendezeitschlitze innerhalb des zweiten Funkkanals, wobei der dritte vorher festgelegte Zeitraum einen der Sendezeitschlitze umfasst und wobei der vierte vorher festgelegte Zeitraum einen der Empfangszeitschlitze umfasst.
• – Einen Schritt der Steuerung der zweiten Benutzerstation in der Weise, dass sie während des zweiten vorher festgelegten Zeitraums innerhalb des ersten Funkkanals ein Kanalkennung-Bestätigungssignal sendet, nachdem sie während des ersten vorher festgelegten Zeitraums das Kanalkennungssignal empfangen hat.
• – Einen Schritt des Austauschs von Daten zwischen der ersten und der zweiten Benutzerstation innerhalb des zweiten Funkkanals, nachdem die erste Benutzerstation das Kanalkennung-Bestätigungssignal während des zweiten vorher festgelegten Zeitraums innerhalb des ersten Funkkanals empfangen hat.
• – Die zweite Benutzerstation bestätigt den Empfang des ersten Bestätigungssignals, wenn sie feststellt, dass die erste Benutzerstation die Übertragung des ersten Rufsignals abgeschlossen hat.
• – Einen Schritt der Steuerung der ersten Benutzerstation in der Weise, dass sie während des ersten vorher festgelegten Zeitraums innerhalb des ersten Funkkanals ein Kanalkennung-Bestätigungssignal sendet, nachdem sie während des zweiten vorher festgelegten Zeitraums das Kanalkennungssignal empfangen hat.
• – Einen Schritt des Austauschs von Daten zwischen der ersten und der zweiten Benutzerstation innerhalb des zweiten Funkkanals, nachdem die zweite Benutzerstation das Kanalkennung-Bestätigungssignal während des ersten vorher festgelegten Zeitraums innerhalb des ersten Funkkanals empfangen hat.
• – Die erste Benutzerstation sendet während Sendezeitschlitzen innerhalb des dritten Funkkanals Daten und empfängt Daten während Empfangszeitschlitzen innerhalb des vierten Funkkanals, und der dritte vorher festgelegte Zeitraum umfasst einen der Sendezeitschlitze.
• – Das beschriebene Verfahren kann um die folgenden Schritte erweitert werden: Steuern der zweiten Benutzerstation in der Weise, dass sie den dritten Funkkanal lokalisiert; Synchronisieren der zweiten Benutzerstation mit dem dritten vorher festgelegten Zeitraum innerhalb des dritten Funkkanals und mit einem vierten vorher festgelegten Zeitraum innerhalb des vierten Funkkanals; und Steuern der zweiten Benutzerstation in der Weise, dass sie während des vierten vorher festgelegten Zeitraums innerhalb des vierten Funkkanals ein zweites Bestätigungssignal sendet, nachdem sie während des dritten vorher festgelegten Zeitraums das zweite Rufsignal empfangen hat.
• – Die erste Benutzerstation sendet während Sendezeitschlitzen innerhalb des dritten Funkkanals Daten und empfängt Daten während Empfangszeitschlitzen innerhalb des vierten Funkkanals, und die zweite Benutzerstation sendet während der Empfangszeitschlitze in dem vierten Funkkanal Daten und empfängt Daten während der Sendezeitschlitze in dem dritten Funkkanal, wobei der dritte vorher festgelegte Zeitraum einen der Sendezeitschlitze umfasst und wobei der vierte vorher festgelegte Zeitraum einen der Empfangszeitschlitze umfasst.
• – Einen Schritt des Austauschs von Daten zwischen der ersten und der zweiten Benutzerstation innerhalb des dritten und des vierten Funkkanals, nachdem die erste Benutzerstation das zweite Bestätigungssignal während des vierten vorher festgelegten Zeitraums innerhalb des vierten Funkkanals empfangen hat.
• – Die erste Benutzerstation sendet während Sendezeitschlitzen innerhalb des dritten Funkkanals Daten und empfängt Daten während Empfangszeitschlitzen innerhalb des vierten Funkkanals, und die zweite Benutzerstation sendet während der Empfangszeitschlitze in dem vierten Funkkanal Daten und empfängt Daten während der Sendezeitschlitze innerhalb des dritten Funkkanals, wobei der dritte vorher festgelegte Zeitraum einen der Sendezeitschlitze umfasst und wobei der vierte vorher festgelegte Zeitraum einen der Empfangszeitschlitze umfasst.
• – Die zweite Benutzerstation sendet während Sendezeitschlitzen innerhalb des vierten Funkkanals Daten und empfängt Daten während Empfangszeitschlitzen innerhalb des dritten Funkkanals, und der dritte vorher festgelegte Zeitraum umfasst einen der Sendezeitschlitze.
• – Das beschriebene Verfahren kann um die folgenden Schritte erweitert werden: Steuern der ersten Benutzerstation in der Weise, dass sie den vierten Funkkanal lokalisiert; Synchronisieren der ersten Benutzerstation mit dem dritten vorher festgelegten Zeitraum und einem vierten vorher festgelegten Zeitraum innerhalb des dritten Funkkanals; und Steuern der ersten Benutzerstation in der Weise, dass sie während des vierten vorher festgelegten Zeitraums innerhalb des dritten Funkkanals ein zweites Bestätigungssignal sendet, nachdem sie während des dritten vorher festgelegten Zeitraums das zweite Rufsignal empfangen hat.
• – Die zweite Benutzerstation sendet während Sendezeitschlitzen innerhalb des vierten Funkkanals Daten und empfängt Daten während Empfangszeitschlitzen innerhalb des dritten Funkkanals, und die erste Benutzerstation sendet während der Empfangszeitschlitze innerhalb des dritten Funkkanals Daten und empfängt Daten während der Sendezeitschlitze innerhalb des vierten Funkkanals, wobei der dritte vorher festgelegte Zeitraum einen der Sendezeitschlitze umfasst und wobei der vierte vorher festgelegte Zeitraum einen der Empfangszeitschlitze umfasst.
• – Einen Schritt des Austauschs von Daten zwischen der ersten und der zweiten Benutzerstation innerhalb des dritten und des vierten Funkkanals, nachdem die zweite Benutzerstation das zweite Bestätigungssignal während des vierten vorher festgelegten Zeitraums innerhalb des dritten Funkkanals empfangen hat.
• – Die zweite Benutzerstation sendet während Sendezeitschlitzen innerhalb des vierten Funkkanals Daten und empfängt Daten während Empfangszeitschlitzen innerhalb des dritten Funkkanals, und die erste Benutzerstation sendet während der Empfangszeitschlitze innerhalb des dritten Funkkanals Daten und empfängt Daten während der Sendezeitschlitze innerhalb des vierten Funkkanals, wobei der dritte vorher festgelegte Zeitraum einen der Sendezeitschlitze umfasst und wobei der vierte vorher festgelegte Zeitraum einen der Empfangszeitzeitschlitze umfasst.
• – Einen Schritt der Steuerung der zweiten Benutzerstation in der Weise, dass sie während des zweiten vorher festgelegten Zeitraums innerhalb des zweiten Funkkanals ein Kanalkennung-Bestätigungssignal sendet, nachdem sie während des ersten vorher festgelegten Zeitraums das Kanalkennungssignal empfangen hat.
• – Einen Schritt des Austauschs von Daten zwischen der ersten und der zweiten Benutzerstation innerhalb des dritten und des vierten Funkkanals, nachdem die erste Benutzerstation das Kanalkennung-Bestätigungssignal während des zweiten vorher festgelegten Zeitraums innerhalb des zweiten Funkkanals empfangen hat.
• – Die zweite Benutzerstation bestätigt den Empfang des ersten Bestätigungssignals, wenn sie feststellt, dass die erste Benutzerstation die Übertragung des ersten Rufsignals innerhalb des ersten Funkkanals abgeschlossen hat.
• – Einen Schritt der Steuerung der ersten Benutzerstation in der Weise, dass sie während des ersten vorher festgelegten Zeitraums innerhalb des ersten Funkkanals ein Kanalkennung-Bestätigungssignal sendet, nachdem sie während des zweiten vorher festgelegten Zeitraums das Kanalkennungssignal empfangen hat.
• – Einen Schritt des Austauschs von Daten zwischen der ersten und der zweiten Benutzerstation innerhalb des dritten und des vierten Funkkanals, nachdem die zweite Benutzerstation das Kanalkennung-Bestätigungssignal während des ersten vorher festgelegten Zeitraums innerhalb des ersten Funkkanals empfangen hat.

The following features - taken by themselves or together with other features - are also indicative of the invention:

• The described method can be extended by the following steps: controlling the first user station in such a way that it locates the second radio channel; Controlling the first user station to transmit a second paging signal within the second radio channel for a third predetermined period of time.
• The first user station transmits data during transmission time slots within the second radio channel and receives data during reception time slots within the second radio channel, and the third predetermined period comprises one of the transmission time slots.
• The described method can be extended by the following steps: controlling the second user station in such a way that it locates the second radio channel; Synchronizing the second user station with the third predetermined time period and a fourth predetermined time period within the second radio channel; and controlling the second user station to transmit a second acknowledgment signal within the second radio channel during the fourth predetermined period of time after receiving the second ring signal during the third predetermined time period.
• The first user station transmits data during transmission time slots within the second radio channel and receives data during reception time slots within the second radio channel, and the second user station transmits data during the reception time slots within the second radio channel and receives data during the transmission time slots within the second radio channel, the third before fixed period comprises one of the transmission time slots and wherein the fourth predetermined period comprises one of the reception time slots.
• - a step of exchanging data between the first and second user stations within the second radio channel after the first user station has received the second acknowledgment signal during the fourth predetermined time period within the second radio channel.
• The first user station transmits data during transmission time slots within the second radio channel and receives data during reception time slots within the second radio channel, and the second user station transmits data during the reception time slots within the second radio channel and receives data during the transmission time slots within the second radio channel, the third before fixed period comprises one of the transmission time slots and wherein the fourth predetermined period comprises one of the reception time slots.
• The described method can be extended by the following steps: controlling the second user station in such a way that it locates the second radio channel; Controlling the second user station to transmit a second paging signal within the second radio channel for a third predetermined period of time.
• The second user station transmits data during transmission time slots within the second radio channel and receives data during reception time slots within the second radio channel, and the third predetermined time period comprises one of the transmission time slots.
• The described method can be extended by the following steps: controlling the first user station in such a way that it locates the second radio channel; Synchronizing the first user station with the third predetermined time period and a fourth predetermined time period within the second radio channel; and controlling the first user station to transmit a second acknowledgment signal within the second radio channel during the fourth predetermined period of time thereafter, after previewing the second call signal during the third period of time.
• The second user station transmits data during transmission time slots within the second radio channel and receives data during reception time slots within the second radio channel, and the first user station transmits data during the reception time slots within the second radio channel and receives data during the transmission time slots within the second radio channel, the third before fixed period comprises one of the transmission time slots and wherein the fourth predetermined period comprises one of the reception time slots.
• - a step of exchanging data between the first and second user stations within the second radio channel after the second user station has received the second acknowledgment signal during the fourth predetermined time period within the second radio channel.
• The second user station transmits data during transmission time slots within the second radio channel and receives data during reception time slots within the second radio channel, and the first user station transmits data during the reception time slots within the second radio channel and receives data during the transmission time slots within the second radio channel, the third before fixed period comprises one of the transmission time slots and wherein the fourth predetermined period comprises one of the reception time slots.
• - a step of controlling the second user station to transmit a channel identification confirmation signal within the first radio channel during the second predetermined period of time after receiving the channel identification signal during the first predetermined time period.
• - a step of exchanging data between the first and second user stations within the second radio channel after the first user station has received the channel identifier confirmation signal during the second predetermined time period within the first radio channel.
• The second user station acknowledges the receipt of the first acknowledgment signal when it determines that the first user station has completed the transmission of the first call signal.
• - a step of controlling the first user station to transmit a channel identifier confirmation signal within the first radio channel during the first predetermined period of time after having received the channel identification signal during the second predetermined period of time.
• - a step of exchanging data between the first and second user stations within the second radio channel after the second user station has received the channel identifier confirmation signal during the first predetermined time period within the first radio channel.
• The first user station transmits data during transmission time slots within the third radio channel and receives data during reception time slots within the fourth radio channel, and the third predetermined period comprises one of the transmission time slots.
• The described method can be extended by the following steps: controlling the second user station in such a way that it locates the third radio channel; Synchronizing the second user station with the third predetermined period of time within the third radio channel and with a fourth predetermined period within the fourth radio channel; and controlling the second user station to transmit a second acknowledgment signal within the fourth radio channel during the fourth predetermined period of time after receiving the second ring signal during the third predetermined period of time.
• The first user station transmits data during transmission time slots within the third radio channel and receives data during reception time slots within the fourth radio channel, and the second user station transmits data during the reception time slots in the fourth radio channel and receives data during the transmission time slots in the third radio channel, the third before fixed period comprises one of the transmission time slots and wherein the fourth predetermined period comprises one of the reception time slots.
• - a step of exchanging data between the first and second user stations within the third and fourth radio channels after the first user station has received the second acknowledgment signal during the fourth predetermined period within the fourth radio channel.
• The first user station transmits data during transmission time slots within the third radio channel and receives data during reception time slots within the fourth radio channel, and the second user station transmits data during the reception time slots in the fourth radio channel and receives data during the transmission time slots within the third radio channel, the third before fixed period comprises one of the transmission time slots and wherein the fourth predetermined period comprises one of the reception time slots.
• The second user station transmits during transmission time slots within the fourth radioka nals data and receives data during reception time slots within the third radio channel, and the third predetermined period comprises one of the transmission time slots.
• The described method can be extended by the following steps: controlling the first user station in such a way that it locates the fourth radio channel; Synchronizing the first user station with the third predetermined time period and a fourth predetermined time period within the third radio channel; and controlling the first user station to transmit a second acknowledgment signal within the third radio channel during the fourth predetermined period of time after receiving the second ring signal during the third predetermined period of time.
• The second user station transmits data during transmission time slots within the fourth radio channel and receives data during reception time slots within the third radio channel, and the first user station transmits data during the reception time slots within the third radio channel and receives data during the transmission time slots within the fourth radio channel, the third before fixed period comprises one of the transmission time slots and wherein the fourth predetermined period comprises one of the reception time slots.
• - a step of exchanging data between the first and second user stations within the third and fourth radio channels after the second user station has received the second acknowledgment signal within the fourth predetermined period within the third radio channel.
• The second user station transmits data during transmission time slots within the fourth radio channel and receives data during reception time slots within the third radio channel, and the first user station transmits data during the reception time slots within the third radio channel and receives data during the transmission time slots within the fourth radio channel, the third before fixed period comprises one of the transmission time slots and wherein the fourth predetermined period comprises one of the reception time slots.
• - a step of controlling the second user station to transmit a channel identifier confirmation signal within the second radio channel during the second predetermined period of time after receiving the channel identification signal during the first predetermined period of time.
• - a step of exchanging data between the first and second user stations within the third and fourth radio channels after the first user station has received the channel identifier confirmation signal during the second predetermined time period within the second radio channel.
• The second user station acknowledges receipt of the first acknowledgment signal when it determines that the first user station has completed transmission of the first call signal within the first radio channel.
• - a step of controlling the first user station to transmit a channel identifier confirmation signal within the first radio channel during the first predetermined period of time after having received the channel identification signal during the second predetermined period of time.
• - a step of exchanging data between the first and second user stations within the third and fourth radio channels after the second user station has received the channel identifier confirmation signal during the first predetermined time period within the first radio channel.

Other embodiments of the invention are for obvious to the skilled person after having the description of here tested disclosed invention and has put the invention into practice.

Claims (20)

Method for establishing a direct connection between user stations in a communication system, wherein the transmission between a base station ( 2 ) and user stations ( 4 ) takes place over a plurality of radio channels, each of which has time slots, the method comprising the following characterizing steps: controlling ( 104 . 105 . 106 ) a first user station ( 4 ) in such a way that it locates a first radio channel among the plurality of radio channels, the transmission of data and control signals between the base station ( 2 ) and at least one user station ( 4 ) takes place, synchronizing ( 104 ) of the first user station with a first predetermined period of time within the first radio channel during which the base station ( 2 ) sends no data and receives no data; and taxes ( 108 ) of the first user station ( 4 ) in such a way that it transmits a first call signal within the first radio channel during the first predetermined period of time in order to be able to switch between the first user station ( 4 ) and a second user station ( 4 ) to establish a direct connection. The method of claim 1, wherein the first predetermined period of time is the flow time between the sending and receiving operations of the Base station ( 2 ). The method of claim 1, wherein the first predetermined period of time comprises the transit time between the transmitting and receiving operations of the base station ( 2 ) includes. The method of claim 1, further comprising the steps of: controlling ( 204 . 205 . 206 ) of the second user station ( 4 ) in such a way that it locates the first radio channel; Sync ( 204 ) of the second user station ( 4 ) with the first predetermined period and a second predetermined period of time within the first radio channel during which the base station ( 2 ) sends no data and receives no data; and taxes ( 214 ) of the second user station ( 4 ) in such a way that it transmits a first acknowledgment signal within the first radio channel during the second predetermined period of time after receiving the first call signal during the first predetermined time period ( 212 ) Has. Method according to claim 4, wherein the second predetermined period of time covers the transit time between the reception and the transmission operation of the base station ( 2 ). Method according to claim 4, wherein the second predetermined period of time covers the transit time between the reception and the transmission operation of the base station ( 2 ) includes. Method according to claim 4, wherein the first radio channel has a first frequency and that following the reception ( 112 ) of the second user station ( 4 ) ( 214 ) first acknowledgment signal transmission between the first and the second user station ( 4 ) via a second radio channel ( 308 . 408 . 512 . 616 ) having a second frequency different from the first frequency, the transmission of data and control signals between the base station (12) 2 ) and at least one user station ( 4 ) does not take place over the second radio channel and whereby a direct transmission between other user stations ( 4 ) does not take place over the second radio channel. The method of claim 4, wherein the first radio channel has a first frequency and the method further comprises the steps of: after receiving ( 112 ) of the first acknowledgment signal control ( 300 ) of the first user station ( 4 ) in that it locates a second radio channel having a second frequency different from the first frequency, the transmission of data and control signals between the base station (12); 2 ) and at least one user station ( 4 ) does not take place over the second radio channel and whereby a direct transmission between other user stations ( 4 ) does not take place over the second radio channel; Taxes ( 302 . 504 ) of the first user station ( 4 ) in such a way that it transmits a channel identification signal identifying the second radio channel during the first predetermined period within the first radio channel. The method of claim 4, wherein the first radio channel has a first frequency and the method further comprises the steps of: after acknowledgment ( 112 ) of the reception of the first acknowledgment signal by the first user station ( 4 ) Taxes ( 400 ) of the second user station such that it locates a second radio channel having a second frequency different from the first frequency, wherein the transmission of data and control signals between the base station ( 2 ) and at least one user station ( 4 ) does not take place over the second radio channel and whereby a direct transmission between other user stations ( 4 ) does not take place over the second radio channel; Controlling the first user station ( 4 ) in such a way that during the second predetermined period within the first radio channel it transmits a channel identification signal identifying the second radio channel. Method according to claim 1, wherein the transmission of data and control signals from the base station to the at least one user station ( 4 ) takes place within the first radio channel having a first frequency, wherein the transmission of data and control signals from the at least one user station ( 4 ) to the base station ( 2 ) within a second radio channel having a second frequency different from the first frequency, the method further comprising the steps of: controlling ( 204 . 205 . 206 ) of the second user station ( 4 ) in such a way that it locates the first radio channel; Sync ( 204 ) of the second user station ( 4 ) with the first predetermined period within the first radio channel and a second predetermined period within the second radio channel during which the base station ( 2 ) sends no data and receives no data; and taxes ( 214 ) of the second user station ( 4 ) in such a way that it sends a first acknowledgment signal within the second radio channel during the second predetermined period of time after receiving the first call signal during the first predetermined time period ( 212 ) Has. The method of claim 10, wherein the im Connection to the reception ( 112 ) of the first acknowledgment signal by the first user station ( 4 ) transmission from the first user station ( 4 ) to the second user stations ( 4 ) via a third radio channel ( 308 . 408 . 512 . 616 ) having a third frequency different from the first and second frequencies, the subsequent transmission from the second user station ( 4 ) to the first user station ( 4 ) takes place via a fourth radio channel ( 308 . 408 . 512 . 616 ) having a fourth frequency different from the first, second and third frequencies, the transmission of data and control signals between the base station (12) 2 ) and at least one user station ( 4 ) does not take place over the third and the fourth radio channel and whereby a direct transmission between other user stations ( 4 ) does not take place over the third and the fourth radio channel. The method of claim 11, further comprising the steps of: controlling ( 400 ) of the first user station ( 4 ) in such a way that it locates the third and the fourth radio channel; Controlling the first user station ( 4 ) in such a way that it transmits a second call signal within the third radio channel during a third predetermined period of time, the second call signal identifying the fourth radio channel. The method of claim 11, further comprising the steps of: controlling ( 400 ) of the second user station ( 4 ) in such a way that it locates the third and the fourth radio channel; Controlling the second user station ( 4 ) in such a way that it transmits a second call signal within the fourth radio channel during a third predetermined period of time, the second call signal identifying the third radio channel. The method of claim 10, further comprising the steps of: after receiving ( 112 ) of the first acknowledgment signal control ( 300 . 500 ) of the first user station ( 4 ) in such a way that it locates the third and the fourth radio channel, the transmission from the first user station ( 4 ) to the second user station ( 4 ) takes place over the third radio channel ( 308 . 408 . 512 . 616 ) having a third frequency different from the first and second frequencies, wherein the transmission from the second user station ( 4 ) to the first user station ( 4 ) takes place over the fourth radio channel ( 308 . 408 . 512 . 616 ) having a fourth frequency different from the first, second and third frequencies, the transmission of data and control signals between the base station (12) 2 ) and at least one user station ( 4 ) does not take place over the third and the fourth radio channel and whereby a direct transmission between other user stations ( 4 ) does not take place over the third and the fourth radio channel; Taxes ( 302 . 504 ) of the first user station ( 4 ) in such a way that during the first predetermined period within the first radio channel it transmits a channel identification signal identifying the third and the fourth radio channel. The method of claim 10, further comprising the steps of: after confirming ( 112 ) of the reception of the first acknowledgment signal by the first user station ( 4 ) Taxes ( 400 ) of the second user station in such a way that it locates a third and a fourth radio channel, wherein the transmission from the first user station ( 4 ) to the second user station ( 4 ) takes place over the third radio channel ( 308 . 408 . 512 . 616 ) having a third frequency different from the first and second frequencies, wherein the transmission from the second user station ( 4 ) to the first user station ( 4 ) takes place over the fourth radio channel ( 308 . 408 . 512 . 616 ) having a fourth frequency different from the first, second and third frequencies, the transmission of data and control signals between the base station (12) 2 ) and at least one user station ( 4 ) does not take place over the third and the fourth radio channel and whereby a direct transmission between other user stations ( 4 ) does not take place over the third and the fourth radio channel; and controlling the second user station ( 4 ) in such a way that during the second predetermined period within the second radio channel it transmits a channel identification signal identifying the third and the fourth radio channel. Method according to claim 1, wherein each user station ( 4 ) is assigned a unique identification number associated with one or more group identification numbers, the first user station ( 4 ) a first identification number and the second user station ( 4 ) is assigned a second identification number, and wherein the step of controlling ( 104 . 105 . 106 ) of the first user station ( 4 ) in such a manner that it locates the first radio channel, following the determination that the first identification number and the second identification number belong to a common group identification number. Contraption ( 4 ) for use in a communication system, the transmission between a base station ( 2 ) and user stations ( 4 ) takes place over a plurality of radio channels, each of which has time slots, the device ( 4 ) Comprises means for performing all the steps of one of the methods according to the claims 1 to 3. Contraption ( 4 ) according to claim 17 for use in the communication system, the transmission of data and control signals from the base station ( 2 ) to the at least one user station ( 4 ) takes place within a first radio channel having a first frequency, wherein the transmission of data and control signals from the at least one user station ( 4 ) to the base station ( 2 ) takes place within a second radio channel having a second frequency different from the first frequency. Contraption ( 4 ) for use with the device ( 4 ) according to claim 17, comprising means for performing all the steps of one of the methods according to claims 4 to 6 and 10. Communication system, whereby the transmission between a base station ( 2 ) and user stations ( 4 ) takes place over a plurality of radio channels, each of which has time slots, the communication system comprising means for performing all the steps of one of the methods according to claims 1 to 16 for establishing a direct connection between user stations.